(19)
(11) EP 0 523 026 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
14.04.1993 Bulletin 1993/15

(43) Date of publication A2:
13.01.1993 Bulletin 1993/02

(21) Application number: 92850165.9

(22) Date of filing: 02.07.1992
(51) International Patent Classification (IPC)5: G01L 5/24, G01L 1/12
(84) Designated Contracting States:
DE FR GB IT SE

(30) Priority: 08.07.1991 SE 9102121

(71) Applicant: Scan-Mag Sense AS
N-3132 Husöysund (NO)

(72) Inventors:
  • Hesthamar, Tore
    S-431 38 Mölndal (SE)
  • Althoff, Frederik
    S-431 39 Mölndal (SE)
  • Larsson, Thomas
    S-421 66 Västra Frölunda (SE)

(74) Representative: Hammond, Andrew David et al
Albihn West AB, P.O. Box 142
401 22 Göteborg
401 22 Göteborg (SE)


(56) References cited: : 
   
       


    (54) System for surveying the loading of fasteners


    (57) The present invention relates to a surveillance system for measuring and surveying e.g. the preload in screws (23) or similar. It comprises a number of sensor systems (1) electrically connected to a common electronic and computing system, each said sensor system (1) comprising sensor means (2) being provided with a magnetoelastic material (6) sensitive to the preloads and a sensing device (3) comprising a coil system at least partly surrounding the sensitive material (6). The sensitive material (6) is excited via the coil system with a frequency of at least 300 kHz so as to make the system insensitive to external disturbing fields.






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